Scientists transform skin cells into functioning liver cells

February 23, 2014
Immunostaining for human albumin (red) and Ki67 (green) shows that human fibroblast-derived hepatocytes replicate both function and proliferation of primary hepatocytes after transplantation into mouse livers. Credit: Milad Rezvani

The power of regenerative medicine now allows scientists to transform skin cells into cells that closely resemble heart cells, pancreas cells and even neurons. However, a method to generate cells that are fully mature—a crucial prerequisite for life-saving therapies—has proven far more difficult. But now, scientists at the Gladstone Institutes and the University of California, San Francisco (UCSF), have made an important breakthrough: they have discovered a way to transform skin cells into mature, fully functioning liver cells that flourish on their own, even after being transplanted into laboratory animals modified to mimic liver failure.

In previous studies on liver-, scientists had difficulty getting stem cell-derived liver to survive once being transplanted into existing liver tissue. But the Gladstone-UCSF team figured out a way to solve this problem. Writing in the latest issue of the journal Nature, researchers in the laboratories of Gladstone Senior Investigator Sheng Ding, PhD, and UCSF Associate Professor Holger Willenbring, MD, PhD, reveal a new cellular reprogramming method that transforms human skin cells into that are virtually indistinguishable from the cells that make up native liver tissue.

These results offer new hope for the millions of people suffering from, or at risk of developing, liver failure—an increasingly common condition that results in progressive and irreversible loss of liver function. At present, the only option is a costly liver transplant. So, scientists have long looked to stem cell technology as a potential alternative. But thus far they have come up largely empty-handed.

"Earlier studies tried to reprogram skin cells back into a pluripotent, stem cell-like state in order to then grow liver cells," explained Dr. Ding, one of the paper's senior authors, who is also a professor of pharmaceutical chemistry at UCSF, with which Gladstone is affiliated. "However, generating these so-called induced pluripotent stem cells, or iPS cells, and then transforming them into liver cells wasn't always resulting in complete transformation. So we thought that, rather than taking these skin cells all the way back to a pluripotent, stem cell-like state, perhaps we could take them to an intermediate phase."

Immunostaining for human albumin (red) and Ki67 (green) shows that human fibroblast-derived hepatocytes replicate both function and proliferation of primary hepatocytes after transplantation into mouse livers. Credit: Milad Rezvani

This research, which was performed jointly at the Roddenberry Center for Stem Cell Research at Gladstone and the Broad Center of Regeneration Medicine and Stem Cell Research at UCSF, involved using a 'cocktail' of reprogramming genes and chemical compounds to transform human skin cells into cells that resembled the endoderm. Endoderm cells are cells that eventually mature into many of the body's major organs—including the liver.

"Instead of taking the back to the beginning, we took them only part way, creating endoderm-like cells," added Gladstone and CIRM Postdoctoral Scholar Saiyong Zhu, PhD, one of the paper's lead authors. "This step allowed us to generate a large reservoir of cells that could more readily be coaxed into becoming liver cells."

Next, the researchers discovered a set of genes and compounds that can transform these cells into functioning liver cells. And after just a few weeks, the team began to notice a transformation.

"The cells began to take on the shape of liver cells, and even started to perform regular liver-cell functions," said UCSF Postdoctoral Scholar Milad Rezvani, MD, the paper's other lead author. "They weren't fully mature cells yet—but they were on their way."

Now that the team was encouraged by these initial results in a dish, they wanted to see what would happen in an actual liver. So, they transplanted these early-stage liver cells into the livers of mice. Over a period of nine months, the team monitored cell function and growth by measuring levels of liver-specific proteins and genes.

Two months post-transplantation, the team noticed a boost in human liver protein levels in the mice, an indication that the transplanted cells were becoming mature, functional liver cells. Nine months later, cell growth had shown no signs of slowing down. These results indicate that the researchers have found the factors required to successfully regenerate liver tissue.

"Many questions remain, but the fact that these cells can fully mature and grow for months post-transplantation is extremely promising," added Dr. Willenbring, associate director of the UCSF Liver Center and the paper's other senior author. "In the future, our technique could serve as an alternative for liver-failure patients who don't require full-organ replacement, or who don't have access to a transplant due to limited donor organ availability."

Explore further: Scientists reprogram skin cells into insulin-producing pancreas cells

More information: Paper: dx.doi.org/10.1038/nature13020

Related Stories

Scientists reprogram skin cells into insulin-producing pancreas cells

February 6, 2014
A cure for type 1 diabetes has long eluded even the top experts. Not because they do not know what must be done—but because the tools did not exist to do it. But now scientists at the Gladstone Institutes, harnessing the ...

Scientists find cell fate switch that decides liver, or pancreas?

February 13, 2014
Harvard stem cell scientists have a new theory for how stem cells decide whether to become liver or pancreatic cells during development. A cell's fate, the researchers found, is determined by the nearby presence of prostaglandin ...

Molecular 'cocktail' transforms skin cells into beating heart cells

February 20, 2014
The power of regenerative medicine appears to have turned science fiction into scientific reality—by allowing scientists to transform skin cells into cells that closely resemble beating heart cells. However, the methods ...

Team discovers new liver cell for cellular therapy to aid in liver regeneration

June 6, 2013
Liver transplantation is the mainstay of treatment for patients with end-stage liver disease, the 12th leading cause of death in the United States, but new research from the Icahn School of Medicine at Mount Sinai, published ...

New discovery on early immune system development

November 12, 2013
Researchers at Lund University have shed light on how and when the immune system is formed, raising hope of better understanding various diseases in children, such as leukaemia.

Recommended for you

Link between cells associated with aging and bone loss

August 21, 2017
Mayo Clinic researchers have reported a causal link between senescent cells - the cells associated with aging and age-related disease - and bone loss in mice. Targeting these cells led to an increase in bone mass and strength. ...

Gut microbes may talk to the brain through cortisol

August 21, 2017
Gut microbes have been in the news a lot lately. Recent studies show they can influence human health, behavior, and certain neurological disorders, such as autism. But just how do they communicate with the brain? Results ...

Are stem cells the link between bacteria and cancer?

August 17, 2017
Gastric carcinoma is one of the most common causes of cancer-related deaths, primarily because most patients present at an advanced stage of the disease. The main cause of this cancer is the bacterium Helicobacter pylori, ...

Two-step process leads to cell immortalization and cancer

August 17, 2017
A mutation that helps make cells immortal is critical to the development of a tumor, but new research at the University of California, Berkeley suggests that becoming immortal is a more complicated process than originally ...

New Pathology Atlas maps genes in cancer to accelerate progress in personalized medicine

August 17, 2017
A new Pathology Atlas is launched today with an analysis of all human genes in all major cancers showing the consequence of their corresponding protein levels for overall patient survival. The difference in expression patterns ...

Female mouse embryos actively remove male reproductive systems

August 17, 2017
A protein called COUP-TFII determines whether a mouse embryo develops a male reproductive tract, according to researchers at the National Institutes of Health and their colleagues at Baylor College of Medicine, Houston. The ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.